From: Mason Kelsey <masonkelsey@...>
Date: 2009-09-21T12:23:21+09:00
Subject: Re: Multi-Dimensional Arrays in Priority Queues

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Tried it but it didn't work.  Made the following change:

require "pqueue"
pq=PQueue.new(proc{|x,y| x[0]<y[0]})
pq.push([[12], [123456780], [123456708]])
pq.push([[23], [123456780], [123456708]])
pq.push([[4], [123456780], [123456708]])
pq.push([[33], [123456780], [123456708]])
pq.push([[02], [123456780], [123456708]])
pq.push([[54], [123456780], [123456708]])
print "size:"+pq.size.to_s+"\n"
print "each_pop: "
pq.each_pop{|x| print x.to_s+" "}
print "\n"
I got the messages:
>ruby simple_pqueue.rb
simple_pqueue.rb:3: undefined local variable or method `x' for main:Object
(NameError)
 from ./pqueue.rb:24:in `[]'
 from ./pqueue.rb:24:in `upheap'
 from ./pqueue.rb:65:in `push'
 from simple_pqueue.rb:5
>Exit code: 1

The "from" error messages appear to be coming from the code inside of the
pqueue class methods.

Doesn't like the brackets.  I tried several variations of this and also got
a message that said the < is an invalid method.  Very strange.  Sorry but
I'm totally confused here.

There must be a way to do this.

No Sam

On Sun, Sep 20, 2009 at 10:31 PM, Mario Camou <mcamou@tecnoguru.com> wrote:

> Hi,
> In the line:
>
> pq.push([2], [123456780], [123456708])
>
> you're not passing in a multi-dimensional array, you're passing 3
> parameters
> each of which is an array. Try with:
>
> pq.push([[2], [123456780], [123456708]])
>
> (notice the double [ at the beginning and the  double ] at the end).
>
> you will also have to change your PQueue creation to something like this:
>
> pq=PQueue.new(proc{|x,y| x[0]<y[0]})
>
> Haven't tested this in irb but it (or something very much like it) should
> work.
>
> -Mario.
>
> --
> I want to change the world but they won't give me the source code.
>
>
> On Mon, Sep 21, 2009 at 04:25, Mason Kelsey <masonkelsey@gmail.com> wrote:
>
> > In my program I need to construct a priority queue that sorts ascending.
> > The basic idea can be expressed in the following simple code that uses a
> > Priority Queue concept.  See:
> > http://www.math.kobe-u.ac.jp/~kodama/tips-ruby-pqueue.html
> >
> > 1   require "pqueue"
> > 2
> > 3   pq=PQueue.new(proc{|x,y| x<y})
> > 4   pq.push(2)
> > 5   pq.push(3)
> > 6   pq.push(4)
> > 7   pq.push(3)
> > 8   pq.push(2)
> > 9   pq.push(4)
> > 10 print "size:"+pq.size.to_s+"\n"
> > 11 print "each_pop: "
> > 12 pq.each_pop{|x| print x.to_s+" "}
> > 13 print "\n"
> >
> > This is clean and simple to understand.  But I need to be able to put
> into
> > the queue several components per push to make an entire record object.  I
> > need to have three components: an integer heuristic value, followed by
> two
> > 9
> > digit configuration patterns, such as
> > pq.push([2], [123456780], [123456708])  But this gives me an argument
> error
> > message:
> > pqueue.rb:4:in `push': wrong number of arguments (3 for 1)
> > (ArgumentError) from pqueue.rb:4
> >
> > or pq.push(2_123456780_123456708) ignores the underscore separators and
> > runs
> > the 3 parts together as one long number.
> >
> > Still learning Ruby and none of the books address multiple dimensional
> > arrays very well.  Is the Priority Queue not able to handle
> > multi-dimensional arrays?  Can this code be modified to allow
> > multi-elements
> > in each push and still sort on the first element?
> >
> > If I cannot use pqueue, is there another required library of methods that
> > will work with three elements in each array entry?
> >
> > Thanks in advance to those of you who can help.  And thanks to all who
> help
> > out on this forum.  Very good forum.
> >
> > No Sam
> >
>

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